How some cities ‘flattened the curve’ during the 1918 flu pandemic

Social distancing isn’t a new idea—it saved thousands of American lives during the last great pandemic. Here's how it worked.

Philadelphia detected its first case of a deadly, fast-spreading strain of influenza on September 17, 1918. The next day, in an attempt to halt the virus’ spread, city officials launched a campaign against coughing, spitting, and sneezing in public. Yet 10 days later—despite the prospect of an epidemic at its doorstep—the city hosted a parade that 200,000 people attended.

Weekly deaths per 100,000 from 1918 pandemic above the expected rate

Duration of social

distancing measures

Philadelphia

Deaths per 100,000 after

24 weeks of pandemic

748

250

200

Philadelphia waited 8 days after their death rate spiked to ban gatherings and close schools. They endured the highest peak death rate of 43 cities studied.

150

100

50

0

1

8

Weeks

16

24

Sep. 11 1918

Feb. 19 1919

San Francisco

673

Deaths per 100,000

150

After relaxing social distancing measures,

San Francisco faced

a strong second wave of deaths.

100

50

0

1

8

Weeks

16

24

New York

452

Deaths per 100,000

New York City began quarantine measures very early—11 days before deaths spiked. The city had the lowest death rate on

the Eastern Seaboard.

150

100

50

0

1

8

Weeks

16

24

St. Louis

358

Deaths per 100,000

150

St. Louis had strong social distanc-

ing measures and a low total death rate. The city successfully delayed its peak in deaths, but faced a sharp increase when restrictions were

temporarily relaxed.

100

50

0

1

8

Weeks

16

24

RILEY D. CHAMPINE, NG STAFF.

SOURCE: Markel H, Lipman HB, Navarro JA, et al. Nonpharmaceutical Interventions

Implemented by US Cities During the 1918-1919 Influenza Pandemic. JAMA.

Philadelphia

Weekly deaths per 100,000 from 1918 pandemic above the expected rate

Deaths per 100,000 after

24 weeks of pandemic

748

Duration of social

distancing measures

250

San Francisco

200

Philadelphia waited eight days after their death rate began to take off before banning gatherings and closing schools. They endured the highest peak death rate of all cities studied.

673

Deaths per 100,000

150

150

After relaxing social distancing measures,

San Francisco faced

a long second wave of deaths.

100

100

50

50

0

0

1

8

WEEKS

16

24

1

8

WEEKS

16

24

Sep. 11 1918

Feb. 19 1919

St. Louis

New York

358

452

Deaths per 100,000

Deaths per 100,000

New York City began quarantine

measures very early—11 days

before the death rate spiked.

The city had the lowest death

rate on the Eastern Seaboard.

St. Louis had strong social distanc-

ing measures and a low total death

rate. The city successfully delayed

its peak in deaths, but faced a sharp

increase when restrictions were

temporarily relaxed.

150

150

100

100

50

50

0

0

1

8

WEEKS

16

24

1

8

WEEKS

16

24

RILEY D. CHAMPINE, NG STAFF. SOURCE: Markel H, Lipman HB, Navarro JA, et al. Nonpharmaceutical Interventions Implemented by US Cities During the 1918-1919 Influenza Pandemic. JAMA.

Flu cases continued to mount until finally, on October 3, schools, churches, theaters, and public gathering spaces were shut down. Just two weeks after the first reported case, there were at least 20,000 more.

The 1918 flu, also known as the Spanish Flu, lasted until 1920 and is considered the deadliest pandemic in modern history. Today, as the world grinds to a halt in response to the coronavirus, scientists and historians are studying the 1918 outbreak for clues to the most effective way to stop a global pandemic. The efforts implemented then to stem the flu’s spread in cities across America—and the outcomes—may offer lessons for battling today’s crisis. (Get the latest facts and information about COVID-19.)

Weekly deaths per 100,000 from 1918 pandemic above

the expected death rate

Deaths per 100,000 after

24 weeks of pandemic

807

Duration of social

distancing measures

Highest

death rate

after 24 weeks

Pittsburgh

Philadelphia

New Orleans

807

748

734

Boston

San Francisco

Denver

672

631

710

Fall River, Mass.

Nashville, Tenn.

Washington, D.C.

621

610

608

Cities that ordered social distancing measures later and for shorter periods tended to have spikes in deaths and higher overall death rates.

Birmingham, Ala.

New Haven, Conn.

Kansas City, Mo.

587

574

592

Baltimore

Providence, R.I.

Omaha, Nebr.

554

559

574

Albany, N.Y.

Newark, N.J.

Buffalo, N.Y.

553

533

530

Portland, Oreg.

Richmond, Va.

Oakland, Calif.

505

508

506

Los Angeles

Spokane, Wash.

Cleveland

482

494

474

New York

Cincinnati

Seattle

452

451

414

Cities that ordered social distancing measures sooner and for longer periods usually slowed infections and lowered overall death rates.

Chicago

Dayton, Ohio

Louisville, Ky.

410

406

373

Rochester, N.Y.

St. Louis

Columbus, Ohio

359

358

312

Lowest death rate

after 24 weeks

Milwaukee

Indianapolis

Minneapolis

359

290

267

RILEY D. CHAMPINE, NG STAFF.

SOURCE: Markel H, Lipman HB, Navarro JA, et al. Nonpharmaceutical Interventions

Implemented by US Cities During the 1918-1919 Influenza Pandemic. JAMA.

Deaths per 100,000 after

24 weeks of pandemic

Duration of social

distancing measures

Weekly deaths per 100,000 from 1918 pandemic above the expected rate

807

Highest

death rate

after 24 weeks

Pittsburgh

Philadelphia

New Orleans

Boston

San Francisco

Denver

Fall River, Mass.

Nashville, Tenn.

Washington, D.C.

807

748

734

710

672

631

621

610

608

Cities that ordered social distancing measures later and for shorter periods tended to have spikes in deaths and higher overall death rates.

Birmingham, Ala.

New Haven, Conn.

Kansas City, Mo.

Providence, R.I.

Baltimore

Omaha, Nebr.

Albany, N.Y.

Newark, N.J.

Buffalo, N.Y.

592

587

574

574

559

554

553

533

530

Portland, Oreg.

Los Angeles

Spokane, Wash.

Cleveland

Richmond, Va.

Oakland, Calif.

New York

Cincinnati

Seattle

505

494

474

452

451

414

508

506

482

Cities that ordered social distancing measures sooner and for longer periods usually slowed infections and lowered overall death rates.

Lowest death rate

after 24 weeks

Dayton, Ohio

Louisville, Ky.

Chicago

Columbus, Ohio

Rochester, N.Y.

St. Louis

Milwaukee

Indianapolis

Minneapolis

410

406

359

373

358

312

359

290

267

RILEY D. CHAMPINE, NG STAFF. SOURCE: Markel H, Lipman HB, Navarro JA, et al. Nonpharmaceutical Interventions Implemented by US Cities During the 1918-1919 Influenza Pandemic. JAMA.

From its first known U.S. case, at a Kansas military base in March 1918, the flu spread across the country. Shortly after health measures were put in place in Philadelphia, a case popped up in St. Louis. Two days later, the city shut down most public gatherings and quarantined victims in their homes. The cases slowed. By the end of the pandemic, between 50 and 100 million people were dead worldwide, including more than 500,000 Americans—but the death rate in St. Louis was less than half of the rate in Philadelphia. The deaths due to the virus were estimated to be about 358 people per 100,000 in St Louis, compared to 748 per 100,000 in Philadelphia during the first six months—the deadliest period—of the pandemic.

Dramatic demographic shifts in the past century have made containing a pandemic increasingly hard. The rise of globalization, urbanization, and larger, more densely populated cities can facilitate a virus’ spread across a continent in a few hours—while the tools available to respond have remained nearly the same. Now as then, public health interventions are the first line of defense against an epidemic in the absence of a vaccine. These measures include closing schools, shops, and restaurants; placing restrictions on transportation; mandating social distancing, and banning public gatherings. (This is how small groups can save lives during a pandemic.)

Of course, getting citizens to comply with such orders is another story: In 1918, a San Francisco health officer shot three people when one refused to wear a mandatory face mask. In Arizona, police handed out $10 fines for those caught without the protective gear. But eventually, the most drastic and sweeping measures paid off. After implementing a multitude of strict closures and controls on public gatherings, St. Louis, San Francisco, Milwaukee, and Kansas City responded fastest and most effectively: Interventions there were credited with cutting transmission rates by 30 to 50 percent. New York City, which reacted earliest to the crisis with mandatory quarantines and staggered business hours, experienced the lowest death rate on the Eastern seaboard.

In 2007, a study in the Journal of the American Medial Association analyzed health data from the U.S. census that experienced the 1918 pandemic, and charted the death rates of 43 U.S. cities. That same year, two studies published in the Proceedings of the National Academy of Sciences sought to understand how responses influenced the disease’s spread in different cities. By comparing fatality rates, timing, and public health interventions, they found death rates were around 50 percent lower in cities that implemented preventative measures early on, versus those that did so late or not at all. The most effective efforts had simultaneously closed schools, churches, and theaters, and banned public gatherings. This would allow time for vaccine development (though a flu vaccine was not used until the 1940s) and lessened the strain on health care systems.

The studies reached another important conclusion: That relaxing intervention measures too early could cause an otherwise stabilized city to relapse. St. Louis, for example, was so emboldened by its low death rate that the city lifted restrictions on public gatherings less than two months after the outbreak began. A rash of new cases soon followed. Of the cities that kept interventions in place, none experienced a second wave of high death rates. (See photos that capture a world paused by coronavirus.)

In 1918, the studies found, the key to flattening the curve was social distancing. And that likely remains true a century later, in the current battle against coronavirus. “[T]here is an invaluable treasure trove of useful historical data that has only just begun to be used to inform our actions,” Columbia University epidemiologist Stephen S. Morse wrote in an analysis of the data. “The lessons of 1918, if well heeded, might help us to avoid repeating the same history today.”